1. Field
The subject technology relates generally to communication devices, and more specifically to methods and apparatus for a radio frequency (RF) signal combiner having an inverted coupler.
2. Background
Conventional beam forming networks typically use costly active microwave monolithic integrated circuits (MMICs) for beam steering. Other all passive beam steering networks employ passive structures like couplers, combiners, phase shifter and the like but traditionally support a narrow band of operation (less than 1 octave). This is often due to the fact that couplers for radio frequency (RF) signals used in beam forming networks have produced poor phase matching and amplitude matching. Furthermore, conventional couplers for wide bandwidth applications require custom tuning and cannot effectively produce controlled coupling. A beam forming network may require multiple couplers in series, and in those instances, the shortcomings of conventional couplers have accumulative effects, producing very large amplitude and phase variations not tolerable by the network.